Forming starting sheets for electrolytic refining of nickel



y 1952 w. J. cook ET AL E 2,597,296

FORMING STARTING SHEETS FOR ELECTROLYTIC REFINING OF NICKEL OriginalFiled Oct. 1, 1948 2 SHEETS--SI-1EET l J: -xrl: I

i I N V EN TOR 5 1/41/7250 Jen/5s 6 0% GXAL y 1952 w. J. cooK ET AL 72,597,296

FORMING STARTING TS FOR ELECTROLYTIC REFI NG 0F NI Original Filed 001:.l, 194 BEETS-- ET 2 INVENTO Patented May 20, 1952 FORMING STARTINGSHEETS FOR ELEC- TROLYTIC REFININ G OF NICKEL Wilfred James Cook andJoseph Howard Tuck, Port Colborne, Ontario, Canada, assignors to TheInternational Nickel Company, Inc., New York, N. Y., a corporation ofDelaware Original application October 1, 1948, Serial No.

Divided and this application June 10,

1950, Serial No. 167,342. In Canada June 12,

4 Claims. (Cl. 204-412) The present invention relates to the art ofproducing electrolytic nickel, and, more particularly, to the productionof starting sheets used as oathodes in the conventional process ofnickel electrorefining.

In conventional practice, starting sheets have been produced by theplating of a thin sheet of substantially pure nickel on a mother plateof stainless steel or other suitably inert metal, such as anickel-chromium alloy, stripping the starting sheet therefrom, and thenmanually straightening the stripped starting sheet prior to its use asthe cathode in the electrolytic refining process. As thus produced, thestarting sheets are in the form of plain blanks or flat sheets which, byreason of their size, relative thinness, and lack of rigidity result introublesome and expensive operational difiiculties. The inherenttendency of the cathode sheets is to warp or curl after a relativelyshort period in the refining bath making it necessary to remove thesheets from the bath and to restraighten them before continuing thegrowth of the cathodes. Such warping of the cathode sheets if allowed toprogress would result in short circuiting between the cathodes andanodes causing current losses, diaphragm failures, and interruption tothe process.

The initial straightening of the starting sheets as manually performedis objectionable under industrial conditions because careless operatorseither do not properly straighten the sheets or, as commonlyexperienced, dirty the face of the sheets leading to undesirable surfaceeffects on the face of the finished cathode known as honeycombing and/orberrying. The manual straightening is moreover costly andlabor-consuming. The further requirement of restraightening encountersstill greater objections and difficulties incident to the nature of theoperation. This necessitates removal of the cathode sheets from the bathwith the coincidental dispersion of electrolyte causing occupationalhazards and interference to good electrical contacts.

While efforts have heretofore been made to remedy the objections anddifficulties, they have shown no substantial degree of success in theelectrolytic refining of nickel largely by reason of the peculiarproperties of this specific metal. For example, the high modulus ofelasticity of the metal renders it extremely difficult to straightenmechanically. In addition, the inherent tendency to form berries atlocal high spots frequently leads to catho de-anode short circuits withthe resulting loss of current. a The attempted solutions of the problempresented have included varied formation of the starting sheets toobtain stiffening effect including corrugating of the sheets which,however, have heretofore proven ineffective and unsatisfactory for thepurpose in its application to practical nickel refining. In thisconnection, it has been found that in the corrugating of the sheets overextended areas of parallel corrugation warping of the sheets occursparticularly during electrolytic separation with resulting shortcircuiting, particularly due to the local area warping or deflection ofthe metal.

In accordance with the present invention, the objections anddisadvantages incident to the warping of the starting sheets have to alarge degree been eliminated'by the provision of novel starting sheetswith special structural arrangements to provide stifiening deformationsof the metal in a special pattern, designed to reinforce or stiffen themetal against bending or warping in all directions, and of a characterpermissible of successful use in practical electrolytic nickel refining.Important features which materially contribute to the successful use inthe specific process comprise an improved starting sheet havingstiffening deformations wherein the major surface areas of the startingsheets are plane or flat surfaces and wherein the deformations of themetal provide elongated channels or ribs of shallow cross-sectional formand in an arrangement of the ribs providing maximum stiffening effect 7.with a minimum deformation of the metal or sheets.

It is an object of the invention in the production of electrolyticnickel to provide an improved method of manufacturing starting sheetsused as cathodes in such manner as to produce a stiffened sheet of acharacter to maintain a straight sheet during the electrolyticseparation and to provide the channel-rib formation by reverselyoffsetting the sheet material to balance or neutralize the warpingtendencies incident to nickel deposition in the process ofelectrorefining.

A further object of the invention is in the production of electrolyticnickel to provide an improved method of manufacturing an improvedstarting sheet inherently stiffened in it structural formation, whereinthe major portion of its surface area will constitute a plane orflattened surface, wherein the stiffening ribs are made by offsettingthe metal and wherein the rib formations are of relatively shallowcross-sectional contour suitable to economic commercial production ofthe novel nickel starting sheets.

Another important object of the invention, involving the elimination ofthe detrimental features of the prior art, as encountered in theelectrolytic production of nickel, is to provide a novel method ofmanufacturing a starting sheet of per fected structure which shall beinherently stiffened against warping in a manner to preserve itsoriginal flat plane during the entire period of electrodeposition in thepractical nickel refining operation.

It is within the contemplation of the invention to effect importantsavings in operational costs in electrolytic refining of nickel whichare likewise accompanied by advantages, such as the maintenance of cleancontacts, resulting in uniformity of voltage with high ampereefficiency.

The invention likewise contemplates an 1111-.

proved method of producing the starting sheets of the characterdescribed wherein the initially stripped sheets are first rollerstraightened and subsequently die-pressed to form, thereby insuringuniform production of inherently stiffened starting sheets which willmaintain their straight condition throughout the practicalrefiningprocess.

A further object of the present invention is to provide an improvedmethod of forming starting sheets for electrolytic refining of nickelwhich compriseselectrodepositing nickel on a stainless steel blank,stripping the deposited nickel sheet therefrom, roll straightening thestripped sheet in repeated'passes with a turning of the sheetintermediate of each pass and finally trimming and. die-pressing thesheet to form a stiffened sheet having a major area of plane surface.

Moreover, the invention provides a process for the production of aninherently rigid starting sheet involvingassociated steps in anelectrolytic nickel refining operation.

The invention further contemplates an improved process for electrolyticrefining of nickel which comprises preparing a. cathode starting sheetby electroplating a stainless steel blank with substantially, purenickel, stripping the nickel sheet from the blank, roll straighteningthe sheet, die-pressing the straightened sheet to provide the sheetwithspaced stiffening deformations occupying a. minor portion only of itssurface area, and employing thesheets so formed as cathodes in therefining process."

Other desirable'features and advantages of the present invention will bemore fully understood by reference to the accompanying which:

Figure 1 illustrates a plan View of a rectangular starting sheetembodying the features of the present invention;

Fig. 2 is a vertical and longitudinal sectional view thereof'taken online 2-2 of Fig. 1;

Fig. 3 is a transverse sectional view thereof taken on line33 of Fig. 1;

Fig. 4 depicts a. sectional view illustrating a portion of the diestructure employed in the production of the startingsheets andillustrating in section a portion of the starting sheet corresponding toa section taken on line 44 of Fig. 1;

Fig. 5 is a similar sectional view of a portion of the mating diesemployed in the offsetting of the metal of the starting sheets whereinthe starting sheet portion illustrated in section is that portion asindicated by the sectional line 5-5 ofFig. 1;

Fig. 6 shows a corresponding view illustrating the production of theportion of the sheet correspondingto the sectional line 66 of Fig. 1,and

Fig. 7 is a similar view of a die formation of modified structure.

In the embodiment of the:invention-illustrated drawings in in thedrawings, the several features are embodied in the production of acathode starting sheet formed as a rectangular blank or sheet of nickel.The rectangular. blank or sheet of nickel in its initial stage isproduced as a plane sheet by the electrodeposition of substantially purenickel upon a blank of stainless steel and by stripping of the depositedsheet nickel from the blank. The sheets as thus produced may, ifdesired, be roller leveled o1- initially straightened and are then, inaccordance with the invention, diepressed for localized deformation oroffsetting of portions of the sheet nickel to provide stiffening orreinforcing ribs or channels in an arrangement such as to stiffen thestarting sheet against bending in all directions. The arrangement issuch that the number and dimensions of the deformations are such thatthe major surface area of the starting sheet is a plane or flat surfaceand the stiffening deformations are such that the sheet is of unchangedthickness throughout. The deformations as shown in the drawings .are intheir cross-sectional contour of shallow depth and relatively largeradius and curvature thereby to provide on one side of the sheet ashallow curve or curved channel and at the opposite side of the sheet anarching or rib formation of substantially corresponding radius. Theseribchannel stiffening deformations by reason of their shallow depth areof a form adapted for their economic production by die-pressing of therelatively high modulus of elasticity metal. Moreover, by reason of theshallow depth of the deformations with relation to their width,,thestiffening effect is provided with avoidance of high spots or ribs of anature tending to buildup or berry during electrodeposition in suchmanner as to interfere with the refining process.

In Fig. 1 of the drawing, there is illustrated a preferred spacing andarrangement of the stiffening deformations formed by die-pressoffsetting of the metal. This spacing and arrangement in a rectangularsheet I comprises diagonally stiffened means, such as deformations 2 and3. Between said diagonal. deformations is a plurality of ribsor'deformations 4 and 5.-which are parallel to the longitudinal edges ofthesheet. A plurality of transverse ribs or deformations 6 and 1 arearranged perpendicular thereto and parallel to the shorter edges of thesheet. The said ribs and deformations are formed'by offsetting them toone side of the sheet. Associated with the longitudinal ribs is a pairofsimilar.reinforcing rib-channels or deformations 8-which are offset tothe opposite'side of the sheetand which are arranged within anintermediate area thereof and parallel to an associated longitudinaledge. Similarly, reinforcing rib-channelsror deformations 9 are arrangedwithin an intermediate area of the sheet and parallelto the transverseor shorter edge thereof. These reinforcing rib-channels or deformationsare designed. to neutralize warping tendencies-as may occur at certainperiods of the building upof-the cathode during electrodeposition.

The starting sheets may have any, appropriate size, say about 29" x 39",with thecurved or arched deformations having a limited or-restricteddepth and width of said about 1%" andabout 1 respectively. The .ratio ofwidth to depth of the deformationhas been found tobe somewhat criticaland is preferably of the orderof 16 to 1. Novel starting sheetsembodying these deformations have, under comparative test with .thecustomarily employed plain or straight starting sheets, shown markedsuperiority in the resulting product without restraightening even thoughthese conventional straight sheets were lifted and restraightened withintwenty-four hours.

Th spacing arrangement of the deformations used by the inventionprovide-s for the major surface area of the sheets to be plain fiatsurfaces and further provides a marginal fiat surface of sufiicient areato permit the attachment of the usual terminal straps employed forsuspending the sheets in the tanks. The flat marginal portions are,accordingly, of a character to insure good electrical contact with thestraps which are customarily secured by spot welds. The starting sheetsmay normally have a thickness of about 0.040 inch.

In Figs. 4 to 6, a suitable arrangement is illustrated for die-pressingthe starting sheets to incorporate therein the stiffening deformationsor ribs in accordance with the present invention. Upper and lower matingdies l0 and II are employed and provided with die inserts I2 and I3having their active or formingsurfaces conforming to the configurationto be produced. In practice, it has been found beneficial, at timespreliminary to the die-pressing of the deformations, to subject thestripped sheets to a roller-straightening operation after which thesheets are diepressed with a simultaneous trimming or shearing of thesheets to proper size. The roller straightening is found to beadvantageous particularly with sheets having low ductility which in viewof the springine-ss of the metal does not readily straighten under thepress. The roll straightening is desirably performed with a single passbut may necessitate repeated passes with a turning of the sheet end forend or lengthwise rolling in reverse directions.

In Fig. 7, a modified die structure is shown wherein the upper dieinsert I2 is formed as a clearance die and wherein the offsetting iseffected entirely by the lower cooperating die insert l3.

The preparation of the starting sheets of the unique structural formresults in substantial operational and maintenance economies,particularly as related to the elimination of the requirement forrestraightening of the sheets during the process and the detrimentalconditions incident thereto.

It is to be observed that the present invention provides an improvedmethod of forming starting sheets especially adapted for use with and incombination with the electrolytic refining of nickel, including thesteps of electrodepositing nickel on a metal blank, stripping the nickeldeposited sheet therefrom, roll straightening the stripped sheet, andfinally die-pressing the sheet to form a stiffened starting sheet havinga major area of plane surface to provide starting sheets which areinherently stiffened to a degree effective to preserve its original flatplane during the entire period of electrodeposition in the practicalnickel refining operation. The requirement of restraightening of thecathode sheets during the refining operation is accordingly eliminatedtogether with the objections as referred to incident to therestraightening operation such as caused by dispersion of theelectrolyte.

While a preferred method of producing starting sheets suited for nickelrefining is described and shown, it will be understood that variationsand modifications thereof may be resorted to without departing from thescope of the invention as defined in the appended claims. For insignedparticularly for meeting the more severe conditions imposed in nickelrefining, it will be understood that certain features thereof may beadvantageously employed in the electrolytic separation of other metalswhich may offer less in difiiculties such as to provide for the economicformation of stiffened starting sheets. Also, the roll-straighteningoperation, as hereinbefore described, may be modified by firststraightening of the sheet through a roll pass and then repeating with arotation of the sheet through a angle instead of the angle ashereinbefore referred to.

The present application is a division of our copending applicationSerial No. 52,302 filed under date of October 1, 1948, now Patent No.2,578,968, issued December 18, 1951.

We claim:

1. The herein described method of forming starting sheets forelectrolytic refining of nickel which comprises electrodepositing nickelon a stainless steel blank to form an electrodeposited sheet, strippingthe said sheet of electrodeposited nickel from said blank, rollstraightening the stripped nickel sheet in repeated passes with turningof the sheet intermediate of each pass, die-pressing said nickel sheetand offsetting multiple spaced deformations located at both sides ofeach central axis of the sheet and extending parallel to the edges ofthe sheet, said multiple deformations being spaced from said edges byplane surface marginal areas and having certain ones offset from oneside of the sheet and others ofiset from the other side of the sheet andforming centered deformations extending diagonally of the sheetincluding deformations coextensive therewith, and controlling saiddeformations to have a depth of about one-sixteenth of an inch and awidth of about one inch whereby a stifiened starting sheet is formedhaving a major area constituted of plane surfaces and a minor areaconstituted of offset portions in the form of shallow elongateddeformations of arched crosssectional contour.

2. The herein described method of forming starting sheets forelectrolytic refining of nickel which comprises electrodepositing nickelon a metal blank to form an electrodeposited sheet, stripping the saidsheet of electrodeposited nickel from said blank, roll straightening thestripped nickel sheet, die-pressing the said nickel sheet and offsettingmultiple spaced deformations located at both sides of each central axisof the sheet and extending parallel to the edges of the sheet, saidmultiple deformations being spaced from said edges by plane surfacemarginal areas and having certain ones ofiset from one side of the sheetand others offset from the other side of the sheet and forming centereddeformations extending diagonally of the sheet, and controlling saiddeformations to have a width to depth ratio of 16 to 1 whereby astiffened starting sheet is formed having a major area constituted ofplane surfaces and a minor area constituted of offset portions in theform of shallow, elongated deformations of arched cross-sectionalcontour extending to one side of the sheet.

'3. The process of electrolytic refining nickel which comprisespreparing cathode starting sheets by electrodepositing substantiallypure nickel on a stainless steel blank, stripping the said sheet ofelectrodeposited nickel from said blank, roll straightening the strippednickel sheet, diepressing the said nickel sheet and offsetting multiple,spaced 'der6rm ations -1ocated at ham sides of each central axis ofthesh'eet and ex: tending parallel to' the edges-of the sheet, saidmultiple deformations being" spaced from said edges by plane surfaceniarginal -areasand havingc'ertain ones offset from one side'of thesheet and others offset from the otherside of the sheet and. formingcenter deformations extending diago nally of the sheet and includingdeformations coextensive therewith; andcontrolling said deformationstohave a width to depth-ratio of 16 to 1 whereby a stiffened startingsheet is formed having a major area constituted of plane surfaces and aminor area cohstitiited ofofiset portionsin theform of shallow elongateddeformationsot arched cross-sectional-contour and-employin'g'the sheetsso formed as cathodes in the-refining proc--- ess whereby warping of thecathodes is materially reduced.

4; Theprocessof electrolyticrefining of nickel being spaced from saidedgesby plane surface marginal areas and havingcertain ones offset fromone side of the sheet and others'offset from the other side of the sheetand with centered deformations extending diagonally of the sheet andincluding a continuous" deformation coextensive with the sheet, andcontrolling said deformations to have a width to depth ratio of 16 to 1whereby a stifiened starting sheet is formed having a major areacon'stitut'd'of plane's'urfaces and a minor-area constituted of offsetportions'in the'form of shallow, elongated deformations of archedcross-sectional contour extending to one side of the sheet and-wherebywarping of-the cathode ismaterially reduced when said stiffened startingsheet is employed as the cathode in the said nickel refiningprocessQ JAMS- COOK.

J OSEPH' HOWARD TUCK."

REFERENCES CITED The following references are of record in the" file ofthis patent:

UNITED STATES PATENTS Number Name Date 1 ,128,676 Garbe'r et al; Feb.16,1915 1,836,368 Eppsteiner et a1; Dec. 15, 1931 2,001,385-Gron'ningsaeter May' 14,1935 2,325,660" Chamberlain -Aug} 3; 19432,421,582 Shepard et a1. Ji1n'e 3', 1947

1. THE HEREIN DESCRIBED METHOD OF FORMING STARTING SHEETS FORELECTROLYTIC REFINING OF NICKEL WHICH COMPRISES ELECTRODEPOSITING NICKELON A STAINLESS STEEL BLANK TO FORM AN ELECTRODEPOSITED SHEET, STRIPPINGTHE SAID SHEET OF ELECTRODEPOSITED NICKEL FROM SAID BLANK, ROLLSTRAIGHTENING THE STRIPPED NICKEL SHEET IN REPEATED PASSES WITH TURNINGOF THE SHEET INTERMEDIATE OF EACH PASS, DIE-PRESSING SAID NICKEL SHEETAND OFFSETTING MULTIPLE SPACED DEFORMATIONS LOCATED AT BOTH SIDES OFEACH CENTRAL AXIS OF THE SHEET AND EXTENDING PARALLEL TO THE EDGES OFTHE SHEET, SAID MULTIPLE DEFORMATIONS BEING SPACED FROM SAID EDGES BYPLANE SURFACE MARGINAL AREAS AND HAVING CERTAIN ONES OFFSET FROM ONESIDE OF THE SHEET AND OTHERS OFFSET FROM THE OTHER SIDE OF THE SHEET ANDFORMING CENTERED DEFORMATIONS EXTENDING DIAGONALLY OF THE SHEETINCLUDING DEFORMATIONS COEXTENSIVE THEREWITH, AND CONTROLLING SAIDDEFORMATIONS TO HAVE A DEPTH OF ABOUT ONE-SIXTEENTH OF AN INCH AND AWIDTH OF ABOUT ONE INCH WHEREBY A STIFFENED STARTING SHEET IS FORMEDHAVING A MAJOR AREA CONSTITUTED OF PLANE SURFACES AND A MINOR AREACONSTITUTED OF OFFSET PORTIONS IN THE FORM OF SHALLOW ELONGATEDDEFORMATIONS OF ARCHED CROSSSECTIONAL CONTOUR.